From the results tabulated in this report the following conclusions may be made:
1.The Bullis fever syndrome is a distinct clinical entity which may be reproduced in humans by the inoculation of blood from febrile cases of the disease.
2.The Bullis fever agent from the blood of febrile cases has been propagated on the yolk sac of the developing chick embryo. Theyolk sac propagated agent reproduced the Bullis fever syndrome in humans after twenty serial transfers in the yolk sac.
3.The Bullis fever agent has been isolated from tick emulsion (A. americanum) from Camp Bullis, and has been propagated in the yolk sac of the developing chick embryo. After the agent was propagated for twelve generations on the yolk sac of the developing chick embryo, it reproduced the Bullis fever syndrome in the human.
4.The immunological responses induced by natural cases of disease by the blood propagated yolk sac strain and by the tick propagated yolk sac strain are the same.
5.There is no immunological relationship between the agent of Bullis fever and the agent of Colorado tick fever.